Various studies indicate that an implanted lead may fail for one or more reasons. For example, a study by Dorwarth et al., “Transvenous defibrillation leads: high incidence of failure during long-term follow-up”, J Cardiovasc Electrophysiol., 14(1):38-43 (2003), found that a majority of lead-related sensing failures were associated with insulation defects that occurred late after ICD placement (6.0+/−1.8 years after implant). Dorwarth et al. recognized that “automated device control features with patient alert function integrated into new devices may contribute to early detection of lead failure”. Thus, a need exists for techniques to detect lead failure.
To date such techniques typically rely heavily on impedance measurement. An excessive lead impedance may indicate loss of a connection due to a conductor fracture and a low lead impedance may indicate a short circuit or alternative conduction path due to an insulation failure. While impedance techniques offer some benefits, they also have some possible disadvantages. For example, a possible disadvantage relates to power consumption in that many impedance techniques rely on use of an applied voltage. Further, impedance techniques may be inadequate for detection of a low impedance insulation failure or defect that could compromise a high energy defibrillation shock or compromise device operation. Various exemplary methods, devices, systems, etc., disclosed herein aim to address lead issues and/or other issues.